A solar eclipse across Europe next Friday will slash generation from solar power plants. Grid operators are pulling out the stops preparing for both massive power supply swings and abnormal power consumption.

By summer the mighty Union for the Co-ordination of Transmission of Electricity (UCTE), whose 240,000 kilometers of high-voltage lines connect 26 European countries, may cease to exist. Europe is not giving up electricity. Electrons will still flow on the world's largest interconnection of power grids. Rather, the 57-year-old UCTE will be subsumed within a new and broader organization designed to, among other improvements, make Europe's grids renewables-ready: the European Network of Transmission System Operators for …